Ethylene from halogenated hydrocarbons

ABSTRACT

A process for the preparation of ethylene from the halodehydrogenation of ethane in the presence of a halogen a hydrogen halide diluent and a fluidized catalyst is disclosed.

nited States Patent Beard, Jr. 1 Jan. 28, 1975 1 ETHYLENE FROM HALOGENATED 3.542.895 11/1970 {Ii US$ 11 260/6833 3.542.897 H 1970 ultlmenu C! All. 260/6833 3.558.735 1/1971 Beard. Jr. 260/6833 [75] Inventor: William Q. Beard. Jr" ic a. 3.658.933 4/1972 B66111. Jr 260/677 XA Kans. 3.658.933 4/1972 Beard. Jr. 260/677 3.702.311 11/1972 Beard. Jr 260/677 XA [73] Assgnee Ehyl cmporatmm 3.7 9.362 10 1973 Beard. Jr 260/677 XA 1 28, 1972 FOREIGN PATENTS OR APPLICATIONS [21] A l. No.1 284,335 969.416 10/1962 GICUI Britain 260/677 XA Related Application Dam Primary E.\'amincrDe1bert E. Gamz [62] D1v1s10n of Ser. No. 841,238,.Iu1y 14, 1969. Pat. No. Assam! Examim,r juaniw M- Nelson 3702311 Attorney, Age/1!. or Finn-Donald L. Johnson; John F. U S Cl 260/677 XA Sieberth; Edgar E. Spielman, Jr. [51] Int. Cl. C07c 11/12 {58] Field 61 Search 260/677 XA, 683.3, 680 E [57] ABSTR ACT A process for the preparauon of ethylene from the [561 References Cited halodehydrogenation 01 eth me in the pres er lce of a UN'TED STATES PATENTS halogen a hydrogen hahde dlluent and a flu1d1zcd catal :t is discl )sed. 2,971,995 2/1961 Argunbright 260/6833 ys I 3.217.064 11/1965 McGreevy ct 61. 260 6833 l Clfllms, N0 Dr wmg ETHYLENE FROM HALOGENATED HYDROCARBONS This is a division, of application Ser. No. 841,238, filed July 14, 1969, now U.S. Pat. No. 3,702,311.

BACKGROUND OF THE INVENTION The present integrated process for the production of vinyl halide begins with the production of ethylene from ethane. Unsaturated hydrocarbons such as ethylene are commonly produced by either thermal cracking or catalytic cracking or a combination of both. In the known processes the principal advantage is low conversion of the saturated hydrocarbon to unsaturated hydrocarbon. In the literature, the reported conversion is rarely greater than about 40 percent. See, for instance, U.S. Pat. No. 3,119,883, U.S. Pat. No. 2,971,995 and British Pat. No. 969,416. It will be seen that product streams containing less than 30 percent of ethylene are not uncommon. In addition to low hydrocarbon conversion, the prior art processes often result in a product containing a variety of materials which are difficult to separate. For instance, in the case where ethane is the feed material substantial quantities of acetylene and methane are often produced. When ethylene is the desired product, serious problems are encountered due to the difficulty of separating these materials. Also, when a catalyst is employed in the known processes, experience has shown that periodic shutdown is necessary due to the fouling of the catalyst with tars and resins. Also, in many cracking operations exceedingly high temperatures are often necessary, eg see U.S. Pat. No. 3,119,883.

A primary purpose of the present invention is the provision of a multi-step process for the production of vinyl halide beginning with the halodehydrogenation of ethane to ethylene and proceeding through the oxyhalogenation of the ethylene to 1,2-dihaloethane and the dehydrohalogenation of the 1,2-dihaloethane to vinyl halide, thereby enabling savings to be effected in one embodiment through recycling the hydrogen halide produced in the vinyl halide step back to the halodehydrogenation step.

Another primary purpose of this invention is to provide a unique process for the halodehydrogenation of ethane to produce ethylene wherein the conversion of ethane to ethylene is substantially increased. Other purposes are the provision of (l) a continuous halodehydrogenation process wherein shutdown due to catalyst fouling is avoided, (2) a halodehydrogenation process which does not require excessively high temperatures and (3) a halodehydrogenation process wherein the products formed are suitable for use in an oxyhalogenation process.

SUMMARY OF THE INVENTION The present invention concerns a process for the halodehydrogenation of ethane to ethylene, the improvement comprising employing a hydrogen halide diluent with the halogen.

The invention further involves a process for the preparation of vinyl halide by cracking dihaloethane which has been prepared by oxyhalogenating ethylene which has been prepared by halodehydrogenating ethane, the improvement comprising recycling the hydrogen halide produced in the cracking to the halodehydrogenation.

In addition the invention provides a process for the preparation of vinyl halide by cracking dihaloethane which has been prepared by oxyhalogenating ethylene which has been prepared by halodehydrogenating ethane, the improvement comprising employing an excess of ethane in the halodehydrogenation and recycling the unreacted part of the excess from the cracking to said halodehydrogenation.

Even further the invention involves a supported catalyst for the production of ethylene by the halodehydrogenation of ethane in the presence ofa halogen and a hydrogen halide diluent which comprises, in combination, from about 0.15 weight percent to about 3 weight percent of a metal halide selected from the group consisting of copper halide and iron halide, the weight percent being based on the total weight of said supported catalyst, and rare earth halide, the weight ratio of said rare earth halide to said metal halide being in excess of 1:1.

The above and other purposes are accomplished step-wise, first by a process for the halodehydrogenation of ethane and the production of ethylene by contacting ethane with a fluidized catalyst, halogen and a hydrogen halide diluent at a temperature above 350C., or preferably from about 400C. to about 650C., and a pressure above atmospheric, or preferably from about one atmosphere to about 30 atmospheres, the fluidized catalyst being composed ofa mixture containing essentially from about 0.15 percent to about 3.0 percent copper or iron halide and from about 5 percent to about 20 percent rare earth halides (hydrated) supported on a fluidized carrier, the percentages being based on the total weight of catalyst and support. The weight percent of the rare earth halides as set forth herein is based on the hydrated form, although such halides need not be hydrated during use.

According to this process, ethane is converted to ethylene in yields as high or higher than 60 percent, without the occurrence of catalyst fouling or the necessity of the excessive temperatures normally associated with cracking operations. Furthermore, this method provides in one embodiment for the economical use of byproduct hydrogen halide, for example hydrogen chloride, which was at one time a troublesome by-product in the petrochemical industry and often disposed of by dumping into pits containing oyster shells, but is now in short supply and strong demand. Moreover, this process utilizes ethane, and abundant and inexpensive hydrocarbon, as a raw material for conversion into the more valuable chemical, ethylene, and eventually into the still more valuable chemical, vinyl halide.

The primary reason for these improved results in halodehydrogenation is the use of a fluidized, supported mixture of copper or iron halide and rare earth halides. In all instances the ratio of rare earth halide (hydrated) to copper or iron halide must exceed 1:1 and should very preferably fall within the ranges hereinafter specified. Preferred conditions are (in weight percent based on the total amount of catalyst and support) a catalyst mixture supported on a fluidized solid carrier containing essentially from 0.15 to about 3.0 percent copper or iron halide and from about 5 percent to about 20 percent rare earth halides (hydrated). Preferably, the catalyst mixture contains from about 0.25 percent to about 0.35 percent copper halide or from about 0.3 percent to about 0.4 percent iron halide and from about 8 to about 15 percent rare earth halides (hydrated). When the amount of rare earth halide and copper or iron halide in the catalyst significantly deviates from that specified above, ethylene is not usually produced and, if produced at all, is produced in only small quantities. lnstead, halogenated hydrocarbons are produced as the major product. This very significant relationship between the amount of copper or iron halide and rare earth halides will be apparent from the examples set forth below.

By the term rare earth halide is meant the halides of the elements in the Lanthanum series, that is, elements having an atomic number of from 57 through 71, and mixtures of these compounds. Included among the rare earth elements are thulium, lanthanum, cerium, praseodymium, neodymium, prometheum, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, ytterbium, lutecium, yttrium. Among the elements cerium is preferred, but praseodymium and neodymium are also excellent catalyst components for the present process. However, since these materials are usually found in nature in mixtures, it is very convenient to use a commercially available mixture. The mixtures used in formulating the catalyst contain rare earth halides, preferably chlorides, or oxides or other mixtures. Examples of minerals containing the rare earths are zircon, thorite, monazite, gadolinite, cerite, orthite, and the like. The mixture known in the art as didymium is suitable, but the mixture extracted from monazite without removal of cerium and thorium is preferred.

The temperature of the halodehydrogenation process should be above 350C. and should preferably range from about 400C. to about 650C. and more preferably from about 475C. to about 600C. It is desirable that the pressure range from about 1 atmosphere to about 30 atmospheres and preferably from about 1 atmosphere to about 20 atmospheres.

The fluidized support for the halodehydrogenation catalyst may be any of the known inert carriers such as sand, diatomaceous earth, alumina, silica gel, pumice, bauxite, chromia-alumina, and the like. Preferably the catalyst support is chromia-alumina, but alumina and silica are highly satisfactory. It is also highly preferable that the particle size of the impregnated catalyst be within the range of from about 120 mesh to about 325 mesh (U.S. Sieve Number). In other words, the preponderance of the catalytic material be no coarser than about 120 mesh and no finer than about 325 mesh. There is no necessity that all particles be of uniform size. The size distribution generally varies throughout the ranges indicated. Usually it is preferred that not more than about 90 percent of the catalyst be finer than 325 mesh and that no more than about 50 percent of the catalyst be coarser than 120 mesh.

The temperature ofthe halodehydrogenation process should be above 350C. and should preferably range from about 400C. to about 650C. and more preferably from about 475C. to about 600C. It is desirable that the pressure range from about 1 atmosphere to about 30 atmospheres and preferably from about 1 atmosphere to about 20 atmospheres.

The fluidized support for the halodehydrogenation catalyst may be any of the known inert carriers such as sand, diatomaceous earth, alumina, silica gel, pumice, bauxite, chromia-alumina, and the like. Preferably the catalyst support is chromia-alumina, but alumina and silica are highly satisfactory. it is also highly preferably that the particle size of the impregnated catalyst be within the range of from about 120 mesh to about 325 mesh (U.S. Sieve Number). ln other words, the preponderance of the catalytic material be no coarser than about 120 mesh and no finer than about 325 mesh. There is no necessity that all particles be of uniform size. The size distribution generally varies throughout the ranges indicated. Usually, it is preferred that not more than about percent of the catalyst be finer than 325 mesh and that no more than about 50 percent of the catalyst be coarser than l20 mesh.

If desired, an alkali metal halide may be added to the halodehydrogenation catalyst mixture in a concentration of from about 0.01 percent by weight to about 5 percent by weight, based on the total weight of catalyst and support. Preferably, it is added in concentrations of about 0.05 percent to about 3 percent, and more preferably from about 0.1 to about 2 percent. The alkali metal halides employed are preferably the halides of lithium, sodium, potassium, rubidium and cesium. The addition of alkali metal halide to the catalyst mixture is a preferred embodiment of the invention, and among the alkali metal halides, lithium halide is most preferred.

Other halodehydrogenation catalyst additives also enhance the performance of the catalyst of this invention. Among such additives, manganese halide in a concentration of from about 1 to about 10 percent by weight, based on the total weight of catalyst and support, is preferred. Other suitable additives include zinc halide, calcium halide, and titanium halide, among which calcium halide is preferred in a concentration of from about 1 to about 10 percent by weight, based on the total weight of catalyst and support.

The addition of iron halide to the copper halide containing catalyst, or vice versa, has also been found beneficial, depending upon the type and quantity of other components in the catalyst. A concentration of iron or copper halide additive of from about l to about 10 weight percent, based on the total weight of catalyst and support, is preferred.

Another important feature of the halodehydrogenation step of this invention is the molar feed ratio ethane/halogen/hydrogen halide which preferably varies in the range of Hi to 2/1 to 4.

The rate of flow of gases through the reaction zone is subject to some variation. Thus, sufficient flow of gases must be provided for fluidization of the supported catalyst. On the other hand, gas flow should not be so extreme as to blow significant quantities of the catalyst out of the reaction zone. It is generally preferable that the superficial linear velocity of the gases entering the reactor be maintained within a range of from about 0.1 to about 5 feet per second. More preferably, for reasons of economy, the superficial linear velocity is maintained from about 0.5 feet per second to about 3.5 feet per second. A suitable contact time is one ranging from about 1 second up to about 20 seconds, and preferably, for best conversion, the contact time should be from about 2 to about l5 seconds.

The halodehydrogenation feed ethane, halogen and hydrogen halide may be fed together into the bottom of the reactor. This can be varied however, and it is indeed often desirable to do so. For instance, two of the reactants are fed into one portion of the reaction zone and the other reactant into another portion.

As shown in the flow scheme depicted in the drawings, the above described ethane halodehydrogenation is the first of a three-step process for producing vinyl halide. One embodiment of this process requires the recycle of part or all of the hydrogen halide from the last step to the first. Another embodiment requires feeding an excess of ethane to the first step in order to react all halogen therein, whereby enough ethylene and hydrogen halide are produced for the oxyhalogenation step. Therefore, in this latter embodiment none, part, or all of the hydrogen halide may be recycled from the last step to the first, while the excess ethane which passes unreacted through the second and third steps may be partly or completely recycled to the first step. As evident, where no hydrogen halide is recycled, the hydrogen halide diluent in the halodehydrogenation may all be produced in situ. Thus, the process envisions complete flexibility with regard to ethane and hydrogen halide recycle so that none, part, or all of either stream may be recycled or sent elsewhere as economy and balance with other facilities and processes dictate.

While the ethane halodehydrogenation process above described in unique, conventional processes known in the art are suitable for the oxyhalogenation and dehydrohalogenation (or thermal cracking) steps. However, according to a preferred embodiment a mixture of from about 1 to about 50 weight percent ethane, from about 40 to about 95 percent ethylene, and from about to about 40 weight percent hydrogen halide are passed from the ethane halodehydrogenation step to the oxyhalogenation reactor wherein there is maintained a pressure of from about 50 to about 250 psig and a temperature of from about 200 to about 400C. The reactants are passed through a supported metal halide catalyst which is maintained in a fluidized state by a reactant flow rate of from about 0.2 to about 2 feet per second at reaction temperature. Contact time is maintained between about 1 and about 20 seconds. Operating under these conditions, from about 60 to about 99 percent conversion of ethylene to 1,2-dihaloethane is achieved.

Also according to a preferred embodiment, the product mixture from the oxyhalogenation step which includes from about 50 to about 90 percent 1,2- dihaloethane, from about 1 to about 20 weight percent ethane, and from about 5 to about 20 weight percent hydrogen halide is passed to a dehydrohalogenation furnace wherein is maintained a temperature of from about 400 to about 600C. and a pressure of-from atmospheric to. about 200 psig. Operating in this fashion, a conversion of 1,2-dihaloethane to vinyl halide of from about 60 to about 90 weight percent is achieved. The vinyl halide is separated from the hydrogen halide by quench and distillation. Uncracked dihaloethane is recycled back'to the furnace.

In the following examples, which are intended to be descriptive rather than restrictive, ethane, halogen, and hydrogen halide were fed into the bottom of a vertically elongated reaction vessel precharged with a fluidizable EXAMPLE I ll catalyst. The catalyst compositions are in weight percent, based on the total weight of catalyst and support. The weight percent of the rare earth halides component (including cerium halide and didymium halide) is 5 calculated on the basis of its hydrated form, although during use, it is not necessarily fully or even partially hydrated.

While the catalytic mixtures of this invention can be deposited upon the fluidized solid support in a number 10 of different ways, a very simple and highly preferred method of impregnating the support is to dissolve in water or an alcohol a weighed amount of the components of the catalyst mixture. A weighed amount of the support is then added to the water or alcohol and the 15 contents stirred until completely homogenous. The

water or alcohol is then evaporated at low temperatures from the so-formed slurry. The evaporation is conveniently done by drying at a low temperature, e.g. about 100C., in a low temperature air circulating oven. The dry impregnated support remaining can then be employed in the process of this invention.

1 claim:

to yield ethylene which comprises contacting ethane with a fluidized supported catalyst, halogen and a hydrogen halide diluent at a temperature above 350C and at a pressure above atmospheric, the catalyst comprising a copper halide or iron halide in a concentration of from about 0.15 to about 3.0 weight/percent, based on the total weight of catalyst and support.

2. The process of claim 1 wherein said catalyst includes rare earth halides, the weight ratio of said rare earth halides to said copper halide or iron halide being greater than 1:1.

3. The process of claim 1 wherein the catalyst additionally contains from about 0.01 to about 5 percent by weight alkali metal halide, based on the total weight of catalyst and support.

4. The process of claim 3 wherein the alkali metal is lithium halide.

5. The process of claim 1 wherein the catalyst includes a compound selected from the group consisting of manganese halide, zinc halide, calcium halide and titanium halide.

6. The process of claim 1 wherein the halogen halide diluent is hydrogen chloride.

7. The process of claim 2 wherein said rare earth halide is cerium halide.

8. The process of claim 1 wherein the temperature is within the range of from about 400C to about 650C and the pressure is within the range of from about 1 to about 30 atmospheres.

9. The process of claim 1 wherein in the halodehydrogenation the molar feed ratio of ethane/halogenl- Molar Feed Ratio Ethane/Ch/HCI 1/1/2 l/1.03/2 Catalyst Composition (Wt.%):

CuCl, 0.30 0.30

Rare Earth Cl (hydrated) 10.0 10.0

C1 0.06 0.06 Catalyst Support alumina alumina Temperature (C) 575 525 Pressure (atm.) l l Ethane Conversion 74.4 72.6 Ethylene Yield 84.5 82.8

1/1/2 ill/2.8

alumina alumina 1. A process for the halodehydrogenation of ethane halogen halide varies in the ranges of 1/1 to 2/1 to 4.

10. The process of claim 1 wherein the halogen diluent is hydrogen chloride; the temperature is within the range of from about 400C to about 650C; the pressure is within the range of from 1 to about 30 atmospheres; the molar feed ratio of ethane/halogen/hydrogen chloride varies within the range of 1/1 to 2/1 to 4; the catalyst support is silica gel, alumina or chromiaaluminia; and the catalyst additionally contains,

i. from about 0.01 to about 5 percent by weight lithium halide based on the total weight of catalyst and support,

ii. from about 1 to about 10 weight percent manganese halide or calcium halide based on the total weight of catalyst and support. and

5 iii. cerium halide in a weight ratio to the copper halide or iron halide greater than 1:1.

11. The process of claim 1 wherein the catalyst support is selected from the group consisting of silica gel.

10 alumina, and chromia-alumina.

Page 1 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 862, 996 DATED January 28, 1975 1NvENTOR(S) I William Q. Beard, Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Cover page in item [57], "No Drawing should read 1 Drawing Page 2 UNITED STATES PATENT GFFICE CERTIFECATE QFQORECTION PATENT NO. 5,862, 995 DATED January 28, 1975 i S) I William BGEtrd, JI'.

it is certified that error appears in the above-irtentified patent and that said Letters Patent are hereby corrected as shown below;

Add the drawing.

- ETHANE ETHANE HALO- DEHYDROGENATION HALOGEN ETHYLENE '1 OXYHALOGENATSON W OXYGEN I DIHALOETHAHE HYDROGEN ETHME DEHYOROHALOGENATEON VINYL HALlDE if and and fieaied this [SEAL] thirtie h ay 0f September 1975 Arrest: I

RUTH c. meow c. Anew-Hg 0mm ARSHALL DANN mnmr'ssr'u/rcr (t /Parents and Trademarks 

2. The process of claim 1 wherein said catalyst includes rare earth halides, the weight ratio of said rare earth halides to said copper halide or iron halide being greater than 1:1.
 3. The process of claim 1 wherein the catalyst additionally contains from about 0.01 to about 5 percent by weight alkali metal halide, based on the total weight of catalyst and support.
 4. The process of claim 3 wherein the alkali metal is lithium halide.
 5. The process of claim 1 wherein the catalyst includes a compound selected from the group consisting of manganese halide, zinc halide, calcium halide and titanium halide.
 6. The process of claim 1 wherein the halogen halide diluent is hydrogen chloride.
 7. The process of claim 2 wherein said rare earth halide is cerium halide.
 8. The process of claim 1 wherein the temperature is within the range of from about 400*C to about 650*C and the pressure is within the range of from about 1 to about 30 atmospheres.
 9. The process of claim 1 wherein in the halodehydrogenation the molar feed ratio of ethane/halogen/halogen halide varies in the ranges of 1/1 to 2/1 to
 4. 10. The process of claim 1 wherein the halogen diluent is hydrogen chloride; the temperature is within the range of from about 400*C to about 650*C; the pressure is within the range of from 1 to about 30 atmospheres; the molar feed ratio of ethane/halogen/hydrogen chloride varies within the range of 1/1 to 2/1 to 4; the catalyst support is silica gel, alumina or chromia-aluminia; and the catalyst additionally contains, i. from about 0.01 to about 5 percent by weight lithium halide based on the total weight of catalyst and support, ii. from about 1 to about 10 weight percent manganese halide or calcium halide based on the total weight of catalyst and support, and iii. cerium halide in a weight ratio to the copper halide or iron halide greater than 1:1.
 11. The process of claim 1 wherein the catalyst support is selected from the group consisting of silica gel, alumina, and chromia-alumina. 